Telephone system



4 sheets-shed 1 May 20, 1941- o. B. BLAcKwELl.

TELEPHONE SYSTEM Filed Jan. y25, 1940 May 20, 1941 o. B. BLAcKwELI.

TELEPHONE SYSTEM Filed Jan. 23, 1940 4 sheets-sheet 2'- l OBBLAC/(WELL May 20, 1941. o. B. BLAcKwELL TELEPHONE SYSTEM Filed Jan. 2s, 1940 4 sheets-sheet :s

' /NVENTOR B O. B. BLACK WELL y May 20, 1941- o. B. BLAcKwELL 2,242,285

TELEPHONE SYSTEM Filed Jan. 25,- 1940 4 Sheets-Sheet 4 HIIIIIIHI- /NVE NmR 0. B. BLACK WELL VB @am ATTORNEY Patented May 20, 2941 2,242,285 TELEPHONE SYSTEM om B. Blackwell, rlamlome, N. Y., assigner to Bell Telephone Laboratories, Incorporated, New i/Zork, N. Y., a corporation of New York Application; January 23, 1940, serial No. 315,149

8 Claims.

This invention relates to telephone systems and has for its object to improve such systems by the use of novel equipment. I

More specically, the invention contemplates the identification of desired pieces of equipment by establishing a field of lights and scanning the ileld by means of an electric eye.

The inyention may be embodied, for example,

in means for selecting an idlejtr'unk `by a marker in the cross-bar system. Lamps corresponding to all the trunks outgoing from an oflice are arranged in a bank, with means for lighting the lamps corresponding to idle trunks. An image of this bank is focussed on the screen of a cathode ray tube, known as an iconoscope, which scans the bank and signals when an idle trunk is reached.

A further feature of the invention contemplates the control of the eectiveness and the scanning of the identification of the selected 'trunk by the use of two radial beam tubes in which the`beams move in synchronism with the two scanning motions of the iconoscope.

These and other features of the invention will be more apparent from a consideration of the ensuing description in connection with the drawings, in which:

Fig. 1 shows, in diagrammatic form, a telephone connection between a calling line and an outgoing trunk, a sender and a. marker, as well as the lamp panel common to the trunks, and the scanning tubes for a. plurality of markers;

Fig. 2 shows the route relays and their crossconnections;

Fg. 3 shows the radial beam tubes which identify the trunk;

Fig. 4 shows the radial beam tubes which control the iconoscope amplifier; and

Fig. shows the manner in which Figs. l. to i are to be arranged.

Certain features ofthe present disclosure form the basisof the copending application of W. H. T. Holden et al., Serial No. 315,142, filed January 23. 1940.

Reference is here made to Patent No. 2,235,803, granted March 18, 1941, to W. W. Carpenter, for a detailed description of a telephone system of the type in which the present invention may be elnployed.

In such a system a calling subscriber, on initiating a call, is connected over primary and secondary line switches to a district iunctor circuit and thrdugh primary and secondary sender lectors to a sender, The subscriber then dials the wanted number which is recorded in the sender. When the sender has received the digits identifying the omce in which the wanted line is located, the sender associates itself with an idle marker through the marker connector and transmits these digits to the marker. AThe marker translates these digits and operates a route relay which identiiies the trunks leading to the wanted one, after which the channels connecting the district junctor with the selected trunk are tested and an idle set of district and omce selectors are operated. When this connection is established, the outgoing trunkv is marked with ground by the district junctor.

According to the present arrangement, a lamp is provided for each outgoing trunk in the lamp bank iil. The trunks outgoing to a particular ofiice are arranged in a -single group in the bank, irrespective of the position of the trunk on the trunk frame. The lamps are allconnected to ground at one side and to battery on the other and, therefore, are normally lighted. When a trunk becomes busy, the busy ground shunts the lamp and extinguishes it.

Whenthe subscriber at substation |05 is connected to district junctor wo and sender mi, he dials the wanted designation. The sender im calls in a marker and transfers the code digits to the marker registers tot. These digits` are translated by means indicated as, translator M39' and cause the operation of one of the route relays identifies the oce in which the wanted line is .located andrthereby the group of trunks to be used. 4

Each marker has an iconoscope such as icono# scope iii, provided with a screen H3 made up of photoelectric elements corresponding in, number to the number of lamps, and these iconoscopes are arranged before the lamp bank so that the image of the lamp array may be focussed by suitable means, indicated by lens H2, on the screen H3, In this way, one lamp bank serves all of the markers of the ,omca The iconoscopes of four markers are indicated in Fig. l. l

The image of the lamp array is swept in the usual manner by a scanning beam of electrons controlled by a sweep circuit providing horizontal and vertical sweep, as shown in U. S. Patent 2,178,464 to M. W. Baldwin, October 31, 1939. Whenever the beam of electrons in the iconoscope traverses an illuminated spot on the screen, there will be an impulse voltage on the iconoscope output lead H20. n

Assuming that there are twenty-live hundred lamps and twenty-five hundred elements, the

frequency oi one sweep will be .one-ftieth of shown) may be used to supply the sweep frequencies. The output of the iconoscope'is fed to amplier H0.

In order to limit the iconoscope amplier' to output therefrom is biocked except when the beam is sweeping over those spots in the screen receiving light from lamps of a particular trunk group. To this end conductors |I4 and IIS are connected to the control circuit 200 which applies either positive or negative potential to them, under the control of the route relays 20|, etc., and the timing circuit of Fig. 4. When either conductor I|4 or conductor I|5 is negative, the output of the amplifier ls blocked, while when both conductors are positive, output from the amplier will be possible.

Theblocking of the output of the ampliner is controlled by two radial beam tubes 450 and 45|, which provide a low voltage, high current beam. Tubes of this type are disclosed in Patent No. 2,217,774, granted Oct, 15,1940, to A. M. Skellett. The beams of the tubes 450 and 45| are rotated by a revolving magnetic eld, as

described in the Skellett patent, produced from a two-phase alternating current supply. Tube 45| operates at high speed and its eld supply, indicated at 452 but not shown in detail, is arranged so that one of its phases is in synchronism with the horizontal sweep supply of the inconoscope I I, Tube 450 operates from a source 453 similar to source 452 but having one of its phases in synchronism with the vertical sweep supply of the iconoscope Each tube has fifty anodes ar- 45| traversing the entire fifty anodes while-'that in tube 450 traverses a single anode. A resistance 454, 455, etc., and 459, 460, etc., is connected between `each of the -anodes of tubes 450 and 45| l and ground, and in parallel therewith a conductor 2,242,285 Vindications ononly aparticular trunk group, the

arc which mayexist in tube 22| by means ofthe commutating condenser 223 and applying posil tive bias to conductor |I5. There is now positive bias on both conductors ||4 and I|5, unblocking the iconoscope amplifier. But tube 224 was operated by the arrival of the beam in tube 45| on anode No. 1 and conductor I I4 was made positive by the beam of tube 450 resting on No. 1 anode in that tube. Owing to thesynchronism between supplies 452 and 453 and the iconoscope sweep sources, however, this occurs when the iconoscope spot just arrives at the rst element in the rst ranged to receive the beam, the beam in tube It is evident that with twenty-five hundred trunks, represented by twenty-five hundred lamps in a bank fifty lamps wide and ilfty lamps high,

any trunk may be identified by two numbers,

each of whichrmay have any value from one to fifty and the two groups of ilfty terminals 2|0 and 2| I, corresponding as they do to the positions of the beams in the tubes 450 and and, therefore, to the position of the scanning beam in the iconoscope, also correspond to the coordinate numbers of the trunks. 4

Specifically, terminal 2|9 on the block 2I2, which may be called the group start terminal, is cross-connected to terminal No. 1 on block 2|0, while terminal 2|8, which may be identified as the trunk group terminal, is cross-connected to terminal No. l of block 2| I. If we assume that this group consists of fifty trunks, the group end terminal 2 I1 will beconnected to terminal No, 50 of block 2|0. If now route relay 204 is'operated, conductor ||4 is connected to terminal 2|3 and receives a positive potential from the anode circuit of f tube 450 so long as the electron beam in the tube rests on anode No. 1.

Terminal 2|9 is connected by relay 204 to re sistance 225 in the input circuit of the thyratron 224. Therefore, as soon as the beam in tube 45| strikes the No. 1 anode, a positive pulse will be 4 sent through resistance 225, operating thyratron 224 through condenser 226, extinguishing anyy row on which the image of lamp I I6 which is the first lamp in the i'lrst` horizontal row of lamp panel |00 is focussed. There will thus be output from the iconoscope amplifier for every lamp y lighted in this row, beginning with the first.

Supposing first that no lamps are found lighted, corresponding to an all-trunks-busy condition, nothing will happen until the beam in tube 45| reaches anode No. 50, which was connected over terminal 2|'| and the outer right contact of route relay 204 to ground through resistance 220. When the beam in tube 45| reaches anode No. 50, a positive impulse will then pass over terminal 2|1 through condenser 222 to the grid of thyratron 22|, causing an arc to strike therein, and extinguishing the arc previously struck in tube 224 by means .of condenser 223. This removes positive bias from conductor ||5 and again blocks the output of the iconoscope amplifier. As no trunk was found, route relay 204 remains operated, relay 228 operates in theoutput of tube 22| and closes a circuit from ground at the inner right contact of relay 204, conductor 229, back contact of relay 302, conductor 3|5, front contact of relay 22B, conductor 230 and thence to the trunks-busy relay 23|, which brings about the transmission of an overow sgnalto the calling subscriber. Relay 23| would be timed in operating to prevent its premature operation.

For route relay 204, terminal 232 has no function. To understand the purpose of this terminal, suppose that the second trunk group, to which route relay 203 appertains, begins with the first trunk of the second row and ends with the thirtyeighth trunk of that row and that the third trunk group to which route relay 202 appertains begins with the thirty-ninth trunk of the second row and ends with the first trunk of the third row. In the case of this third group, group start terminal 2 5 is connected to terminal 39 of block 2|0, trunk group terminal 2|5 is connected to terminal No. 2 of block 2| I and group end terminal 2|3 is connected to terminalNo. l of block radial beam tubes like tubes 450 and 45|, but

have modulating or control grids 303 and 304 which are normally so biased as to suppress ythe beam. The field coils of tubes 300 and 30| are excited from the same sources 453 and 452 as are the ileld coils of tubes 450 and 45|, respectively.

Therefore, the beams in tubes 300 and 30|, when lthey exist, agree exactly in position with rthose in tubes 450 and 45|, respectively.' The output of the iconoscope amplifier I0 is fed to the control grids of tubes 300 and 30| by means of transformer 301, so that when the iconoscope beam strikes an illumina-ted screen element, and the amplifier is unblocked, the impulses to the grids 303 and 304 cause the beams of the tubes 300 and 30| to ilash the anodes of these tubes and the beams will encounter the anodes having the same positions in tubes 300 and 30| as those in tubes 450 and 45| on which the beams of the latter tubes are resting. This iiash of the beams will cause one of the fifty cold cathode tubes 308, etc., associated with tube 300 to break down and also one of the iifty tubes 358, etc., associated with tube 30| to breaky down.' Since the upper winding of relay 302 is included in the output of the cold cathode tubes, it will operate and open the circuit of trunks-busy relay 23 I Art -the same time, the impulse generated in the lower winding of relay 302 will cause tube 22| 'tooperate, extinguishihg the arc in tube 224 and again disv'abling the iconoscope amplifier so that only one cold cathode tube operates in each of the groups associated with tubes 300 and 430 I The cathode circuits of tubes .308, 309, 358, 359, etc., pass through the windings of a crosscoil switch 350 of the type described and claimed in Patent No. 2,187,115 to W. B. Ellwood and W. H.` T. Holden, granted January 16, 1940. This switch has ity vertical coils 328, 329, etc., and iiity horizontal coils 368, 369, etc., with a single pair of contact springs at each cross-point, whereby it includes twenty-uve hundred contacts. One spring of all of these pairs is grounded, so that the operation of the switch connects ground to Cil circuit, means to control the lighting of. said lamps in accordance with the busy or idle condition of said circuits, iconoscope means to scan said bank of lamps, and means responsive to scanning an illuminated poinrt on said bank to stop the scanning operation and to identify the corresponding circuit.

4. In a telephone system, a plurality of circuits, a bank of lampscontaining one lamp for each circuit, means to control thelighting of said lamps in accordance with the busy or idle condition of said circuits, means to scan said bank of lamps, circuit controlling means driven in synchronism with said scanning means, andmeans responsive to scanning an illuminated ,point on said bank to cause said circuit controlling means to stop the scanning operation and to identify the corresponding circuit.

5. In a telephone system, a plurality of circuits, a bank of lamps containing one lamp for each circuit, means to control theA lighting of said lamps in accordance with the busy or idle condition of said circuits, a cathode ray tube, means to i'o'cus an image of said bank of lamps on the screen of said tube, means to scan said screen, and means responsive to the cathode ray beam striking an illuminated point on the screen to stop the scanning operation and to identifythe corresponding circuit.

6. In a telephone system, a cuits, a bank of lamps containingone lamp for each circuit, means to control the lighting of said i lamps in accordance with the busy or idle condithe particular conductor corresponding to the and tubes of Fig. 2. However, the time for holding the marker is so short that probably this would be satisfactory only if non-lamentary lamps were used.

The advantages of -this arrangement lie both in the saving of equipment and in the saving of time, particularly where large trunk groups are involved. A

What is claimed is:

1. The method of selecting an idle telephone trunk which comprises lighting lamps corresponding lto idle trunks in a, lamp sank, scanning an image of said bank by means of an iconoscope and operating trunk identifying means in accordance with the position of the iconoscope beam when it traverses the image of a lighted lamp.

2. The method'of selecting an idle telephone trunk which comprises lighting lamps corresponding to idle trunks in a lamp bank, scanning an image of said bank by means of an iconoscope, driving auxiliary cathode ray tubes in synchro'- nism with said iconoscope, activating said auxiliary cathode ray tubes when the beam of said iconoscopetraverses the image of a lighted lamp,

and operating trunk identifying means in accordance with the positions of the cathode ray tube beams when activated.

3. In a telephone system, a plurality of circuits, a bank of lamps containing one lamp for each ning operation and to identify the corresponding tion of said circuits, a plurality of control devices, a cathode ray tube associated with each of said devices, means to focus an image of said bank of lamps on the screens of said tubes, means in each tube to scan said screen, and means responsive to the cathode ray beam striking an il,- luminafted point on the scre n to stop the scanning operation and to identi y the corresponding circuit and to associate said control device with` said circuit.

'L-In a telephone system, a plurality of circuits, a bank of lamps containing one lamp for each circuit, means to control the lighting of said lamps in accordance with the busy or idle condition of said circuits, a cathode ray tube, means to focus an image of said bank of lamps on the screen of said tube, means to scan said screen, circuit controlling means driven in synchronism' with the beam of said cathode ray tube, and means responsive :to the cathode ray beam striking an illuminated point on the screen to cause said circuit controlling means to stop the scancircuit.

8. In a. telephone system, a plurality of circuits, a bank of lamps containing one lamp for each circuit, means to control the lighting of said lamps in accordance with the busy or idle condition of said circuits, a cathode ray tube, means to focus an image of said bank of lamps on the screen of said ftube, means to scan said screen, cathode ray circuit controlling means driven in synchronism with the beam of said cathode ray tube, and means responsive :to the cathode ray beam striking an illuminated point on the screen to .activate vsaid circuit controlling means to stop the scanning operation and to identify the corresponding circuit.

OTTO B. BLACKWELL.

plurality of ciry 

